Java's Arrays.fill() with multidimensional array [duplicate]

Question

I have a large 2D array:

int[][] matrix = new int[10000][1000];

The program needs to use frequently:

Arrays.fill(int[] a, int fromIndex, int toIndex, int val);

But sometimes it need to fill a row, and sometimes a column. For example, I can fill a row 200 by 1 from 10 to the end:

Arrays.fill(matrix[200], 10, 1000, 1);

But how to fill a column without for()? Is there a data structure that allows to perform both operation with speed, comparable to Arrays.fill() ?

@MattBall, I don't think so. The question is about filling the other dimension, i.e. matrix[0][0], matrix[1][0], etc.... — Serg
– Serg, Commented Jun 1, 2013 at 0:30
It's all the same. You have to use a for loop, either implicitly or explicitly. Arrays.fill() just happens to hide the loop from you. — Matt Ball
– Matt Ball, Commented Jun 1, 2013 at 0:31

FDinoff · Accepted Answer · 2013-06-01 00:30:00Z

4

if you look at the source code (which is copied below) for Arrays.fill() you will find that its only a for loop.

public static void fill(int[] a, int fromIndex, int toIndex, int val) {
    rangeCheck(a.length, fromIndex, toIndex);
    for (int i=fromIndex; i<toIndex; i++)
        a[i] = val;
}

So writing a for loop to fill the columns of the array would be the same sort of code that Arrays.fill() is giving you.

answered Jun 1, 2013 at 0:30

FDinoff

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1 Comment

Serg Over a year ago

Thanks. I thought that Arrays.fill() has and advantage against for(), like System.arraycopy() has.

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